The present invention relates to improvements in apparatus for transmitting motion from driving to driven components in transmission systems and/or other units of machine tools. More particularly, the invention relates to improvements in apparatus for transmitting motion to tools or the like in machines for the processing of tobacco, especially in packing machines for cigarettes or other smokers' products.
In a cigarette packing machine, the tools which fold, crease, tuck and/or otherwise manipulate or treat blanks, partly finished packs and/or finished packs for smokers' products perform a number of different movements. Such movements include reciprocatory, oscillatory, rotary, pure translatory and/or other movements. As a rule, all moving components derive motion from a main drive shaft which, in turn, receives motion from the output element of a prime mover. The movements of all, or nearly all, driven components must be synchronized with a high degree of accuracy and reproducibility. This will be readily appreciated by taking into consideration the delicate nature of cigarette packs, their parts and their contents. The blanks which are to form parts of packs are often draped around arrays of cigarettes so that such blanks must be folded gently in order to avoid damage to the contents. In many instances, a cigarette pack consists of at least three parts, namely an inner envelope which is made of metallic foil, an outer envelope which consists of soft paper or relatively lightweight cardboard (depending upon whether the pack is a soft pack or a so-called flip-top or hinged-lid pack), and a revenue label which is applied over one end of the outer envelope. Furthermore, many packs include third or outermost envelopes consisting of transparent synthetic plastic material and provided with customary tear strips. The parts of such packs must be assembled with a high degree of accuracy because even minor shifting of one blank with respect to the other blank or blanks necessitates segregation of the respective pack from satisfactory packs. Such high degree of accuracy must be achieved while the packing machine turns out up to and in excess of 400 commodities per minute.
Packing machines for cigarettes embody a substantial number of tools including levers, arms, blades, projections and/or others which are operated in synchronism and the driving components for which receive motion from the main drive shaft. The tools and/or the actuating elements therefor receive motion from the main drive shaft through the intermediary of gear trans, linkages, chain drives, belt drives and/or a combination of these. In a modern cigarette packing machine, the actuating elements for blank folding, tucking, creasing, coating or other tools normally include disk-shaped, cylindrical and/or otherwise configurated cams.
At the present time, the nature of transmissions, components of transmissions and tools which manipulate the blanks in a packing machine is determined in advance. However, the exact relationship between the driven and driving components is finalized during actual assembly of the machine. For example, the angular positions of cams with respect to shafts which transmit torque thereto, between the shafts and driving gears therefor as well as between the gears and the main drive shaft are normally determined during actual assembly and testing of the machine. Such mode of coupling the driving and driven components to each other is considered desirable and necessary in order to make sure that the movements of all driven components will be properly coordinated for the making of high-quality packs. The final attachment of driven components to associated driving components is performed by resorting to upsetting or an analogous technique. It is also known to resort to clamps and similar coupling devices which are designed to hold two or more separably connected components in a predetermined position with respect to each other.
The just described presently preferred procedure in assembling transmissions and other units of cigarette packing and like machines exhibits a number of serious drawbacks. First of all, the final assembly of the machine takes up a substantial amount of time because the person or persons in charge must couple a large number of driven components with associated driving components. Thus, each and every tool which is to deform and/or otherwise treat a blank in order to convert it into a part of a cigarette pack must be fixed to the corresponding motion transmitting element or elements in a separate step, often by resorting to special tools. Secondly, it was considered advisable to avoid the making of more or less permanent connections between driving and driven components in order to allow for rapid separation and replacement of defective components. However, it has been found that the heretofore known couplings cannot be reassembled with a desired degree of accuracy after a driven component has been temporarily detached from the associated motion transmitting component. Therefore, renewed mounting of temporarily detached components invariably necessitates lengthy experimentation in order to insure proper synchronization with movements of components which were not separated from the machine. For example, when a driven component is secured to a shaft by upsetting, the deformation must be eliminated (at least to a certain extent) if the driven component is to be detached from the shaft. Consequently, when such driven component is to be reattached to the shaft, it is difficult to find the exact angular position which is best suited to insure proper cooperation of the driven component with other component or components of the machine.